Part 31 (1/2)

6. =Betula ngra=, L. (RIVER OR RED BIRCH.) Leaves 2 to 3 in. long, rhombic-ovate, acute at both ends, distinctly doubly serrate, bright green above; glaucous beneath when young; on petioles only 1/6 their length. Twigs brown to cinnamon-color, and downy when young. A medium-sized tree, 30 to 50 ft. high, usually growing on the edges of streams, the old trunks having a very s.h.a.ggy, loose, torn, reddish-brown bark. Wild in Ma.s.sachusetts, south and west; often cultivated.

GENUS =84. aLNUS.=

Shrubs or small trees with deciduous, alternate, simple, straight-veined leaves with large stipules that remain most of the season. Flowers in catkins. Fruit a small, scaly, open, woody cone, remaining on the plant throughout the year.

* Native species; growing in wet places. (=A.=)

=A.= Leaves rounded at base; whitened beneath; found north of 41 N. Lat 1.

=A.= Leaves acute or tapering at base; southward. (=B.=)

=B.= Flowering in the spring 2.

=B.= Flowering in the autumn 3.

* Cultivated species; from Europe; will grow in dry places 4, 5.

[Ill.u.s.tration: A. incana.]

1. =alnus incana=, Willd. (SPECKLED OR h.o.a.rY ALDER.) Leaves 3 to 5 in.

long, broadly oval or ovate, rounded at base, sharply serrate, often coa.r.s.ely toothed, whitened and mostly downy beneath; stipules lanceolate and soon falling. Fruit orbicular or nearly so. A shrub or small tree, 8 to 20 ft. high, with the bark of the trunk a polished reddish green; common along water-courses north of 41 N. Lat.; sometimes cultivated.

[Ill.u.s.tration: A. serrulata.]

2. =alnus serrulata=, Willd. (SMOOTH ALDER.) Leaves 2 to 4 in. long, thickish, obovate, acute at base, sharply and finely serrate, green both sides, smooth or often downy beneath; stipules yellowish green, oval, and falling after 2 or 3 leaves have expanded above them. Fruit ovate.

Rather a shrub than a tree, 6 to 12 ft. high, common along streams south of 41 N. Lat. In the Southern States it sometimes forms a tree 30 ft.

high.

[Ill.u.s.tration: A. maritima.]

3. =alnus maritima=, Muhl. (SEASIDE ALDER.) Smooth; leaves oblong-ovate to obovate, with a tapering base, sharply serrulate; petiole slender; color bright green, somewhat rusty beneath. Flowering in the autumn.

Fruiting catkin large, to 1 in. long, in. thick, usually solitary, ovoid to oblong. A small tree, 15 to 25 ft. high. Southern Delaware and eastern Maryland, near the coast.

[Ill.u.s.tration: A. glutinsa.]

4. =alnus glutinsa=, L. (EUROPEAN ALDER.) Leaves roundish, wedge-shaped, wavy-serrated, usually abrupt at tip, glutinous; sharply and deeply incised in some varieties. Fruit oval, in. long. A medium-sized tree, 25 to 60 ft. high, of rapid growth, often cultivated under several names; the most important being vars. _laciniata_ (cut-leaved), _quercifolia_ (oak-leaved), and _rubrinervis_ (red-leaved).

[Ill.u.s.tration: A. cordiflia.]

5. =alnus cordiflia=, Ten. (HEART-LEAVED ALDER.) Leaves heart-shaped, dark green and s.h.i.+ning. Flowers greenish-brown, blooming in March and April, before the leaves expand. A large and very handsome Alder, 15 to 20 ft. high, growing in much dryer soil than the American species.

Cultivated from southern Europe. Hardy after it gets a good start, but often winter-killed when young.

GENUS =85. CoRYLUS.=

Low trees and large shrubs with simple, alternate, deciduous, doubly serrate, straight-veined leaves. Flowers insignificant, in catkins in early spring. Fruit an ovoid-oblong bony nut, inclosed in a thickish involucre of two leaves with a lacerated frilled border; ripe in autumn.